This invention relates to a method for recovering hazardous wastes embedded or trapped on phenolic resin filters. More specifically, this invention relates to a method of treating filter cartridges of phenolic resin material which may contain hazardous waste, to remove the filter cartridge and hazardous waste from the filter cartridge housing in a safe manner which will not expose the operators or the environment to the hazardous material.
Phenolic resin filters are described in U.S. Pat. Nos. 2,539,767 and 2,539,768 which issued to L. E. Anderson in January 1951, and incorporated herein by reference. Phenolic resins are very stable and inert to most environmental conditions. Because of these physical properties, filter cartridges of phenolic resins are available in a variety of filter sizes and with a wide range of filtering capabilities down to a single micron. These filter cartridges, enclosed in a reusable shell or cartridge housing of metal such as stainless steel, are often used for the removal of hazardous particulate matter from a variety of process streams and other solutions. These hazardous materials may include heavy metals such as Ni, Cd, Ag, As, Cr, Tl, Se, etc., as well as radioactive materials resulting from nuclear fuel reprocessing or other nuclear activities. For example, during the dismantling of the Three Mile Island (TMI) nuclear rector, it was to decontaminate the reactor cooling water before it could be removed from the reactor. As part of the decontamination process, the water was first passed through a series of phenolic resin filters encased in stainless steel housing, to remove insoluble radioactive particulate matter from the water before the water could be treated further. The contaminated filters cartridges and cartridge housings were placed in shipping casks and transported to temporary storage.
The problem then, is to provide permanent disposal of the hazardous material contained on the filters.
Disposal of the contaminated filters to a landfill is unsatisfactory because the hazardous material is not a permanent part of the filter and is susceptible to leaching from the filter material and, subsequently from the landfill, so that is could ultimately contaminate the ground water. Furthermore, the filters are shipped in a dry state so that removal of the filter cartridges from the cartridge holders can result in the release of a considerable quantity of heavy metal and/or radioactive material into the environment. This is hazardous not only to the environment, but to the personnel who are recovering the cartridges from the cartridge holders.
Furthermore, recovery of the hazardous material from the phenolic resin filters is desirable for several reasons. Some of the heavy metals, such as silver, have an intrinsic value which makes their recovery of interest. Other heavy metals and the radioactive wastes, as noted above, can cause long-term environmental problems if they are not disposed of in a manner that would preclude the waste, nuclear or heavy metal, from contaminating the groundwater or atmosphere at some time in the future.
It would be preferred to recover the filters containing the hazardous material from the filter housings in a remote manner so that it could be accomplished without endangering either the personnel performing the recovery operation or the environment. Recovery of the filter material and the hazardous waste contained thereon would then permit processing of the waste into a medium which could not only reduce the volume of the waste which must be stored, but would prevent release of hazardous material into the environment. This would eliminate the uncertainties associated with long term storage of materials of this type.
The difficulty however, is the removal of the phenolic resin filters containing the hazardous material from their cartridge housings in a environmentally safe manner and the recovery and separation of the hazardous waste from the phenolic filters. Since solvents are not effective for dissolving the phenolic resins, there has been no known method of effectively recovering these wastes from the phenolic filters, so that the wastes can be safely processed.